Dipole is known for its superb usage as a linear antenna. However dipoles and also monopoles can not be implemented as an internal antenna in devices that include a Printed Circuit Board (PCB). In many communication devices, such as cellular handset, there is a grounding problem associated with the presence of the PCB acting as a ground. For example, in cellular handsets and other mobile device with RF communication capabilities the PCB does not allow using such a monopole/dipole antenna.
Moreover, antennas are commonly made of metal of high conductivity such as aluminum or copper. In order to realize a transparent antenna, one needs to use a transparent conducting material whose conductivity is much lower than that of metals. The challenge is how to produce a high performance antenna (like dipole) in spite of the conductivity of currently available transparent conducting materials. Various transparent antennas have been proposed so far such as that disclosed in a thesis submitted to the faculty of The University of Utah by J. R. Saberin, “Optically Transparent Antennas for Small Satellites”, 2010. However, the proposed transparent antennas having major feeding problems which, for example, results in the reduction of emitted signal over the transparent radiation surface of such antennas (see, for example, Balanis, Antenna theory: “Analyze and Design”, Wiley, New York, 1966).
It is an object of the present invention to provide a flat or flexible surface RF antenna which is high performance achieving with only one radiating element (not two elements, like in dipole or monopole which requires a ground).
It is another object of the present invention to use a transparent material with the increased resistance as an RF antenna.
It is yet another object of the present invention to overcome the feeding problems of the transparent antennas proposed in the prior art.
Other objects and advantages of the invention will become apparent as the description proceeds.